We propose to continue to study the role played by command interneurons in the control of stereotyped behavior. We will continue to establish the location of command fibers in the central nervous system and to describe their effects on behavior when stimulated. These refined neural maps of identified neurons will allow us to locate selected units for more detailed study. We will inject certain of the command interneurons with cobalt chloride to glean their structure and attempt to find the means by which they distribute excitation and inhibition to the network of neurons which ultimately provide motor programs underlying the behaviors they evoke. We plan to implant electrodes at the sites of selected command fibers in the nerve cords. Knowing the behavior that these interneurons evoke, we hope to correlate ongoing neural activity in the command fiber with the behavior as it appears in freely behaving animals. We will also continue to study the distribution of unique identified interneurons in related species of animals in an effort to find the rules for their genetic retention or loss. Finally there will be further work directed toward construction of the neural system underlying circadian locomotory rhythms.